either side/both sides

Both sides is more correct in this sense.

"Either" denotes a one-or-the-other relationship. Both means... well, both.

"Either" is mutually exclusive. "Both" is inclusive. Meaning, either would be used to clarify opposing sides. Both would be used to clarify both options possible.

miles said:

Thanks, but are you sure?

Here's sentence from DUMA KEY by Stephen King:

I discovered Tessie and Laura sitting on either side of my bed.

And another from Heart Shaped Box by Joe Hill:

He had spent most of his childhood sharing his bed with dogs, sleeping with one on either side.

I was wondering if there are instances where it's better to use "either" over "both," but I'm pretty sure "either" means "both" when used in this way.

Click to expand...

Both are perfectly acceptable, but "Both" is more clear. "Either" offers a possible misunderstanding.

Really, it's a matter of choice. But you asked, and I chose both. So there.

Change either to both in those example sentences above and you will have an impossible situation -- a person or thing in two places at once.. Use whichever one makes your meaning clearest, depending on context. Sometimes it doesn't matter, sometimes it matters very much.

X and Y sat on either side = one sat on one side, one on the other.

Xes and Ys sat on both sides = they were indiscriminately mixed on *ahem* either side.

She set the dolls one on each side of the bookshelves
(very determinate)
or
She set the dolls on either side of the bookshelves
She set the dolls on both sides of the bookshelves
(there may be a whole mob of dolls, or just two)

He set a rock on either side of the post to brace it.
He set rocks on both sides of the post to brace it. (or on either side)